Consider the following reaction between zinc and oxygen and choose the correct options out of the options given below:
2 Zn (s) + O2 (g) → 2 ZnO (s);ΔH = – 693.8 kJ mol–1
Reason:
ΔH =ΣEnthalpy of formation of product –
ΣEnthalpy of formation of reactant
= [2ΔfHZnO] - [2ΔfHZn+ ΔfHO2]
[2ΔfHZnO] = ΔH + [2ΔfHZn+ ΔfHO2]
As, above reaction is an exothermic reaction, heat will be released, so ΔH will be negative.
iii) As per the sign convention, the negative sign of ΔHindicates that the reaction is exothermic which means heat is released.